Field of the Invention
The present invention relates to alpha amylases and to their application in the food, feed and non-food industry.
Description of Related Art
For many years alpha amylases have been used in the baking industry as processing aids. These enzymes are capable of hydrolysing (1→4)-α-D-glucosidic linkages in polysaccharides containing three or more (1→4)-α-linked D-glucose units. Such linkages are found in starch, the major constituent of most types of flour. Flour quality can vary greatly, depending among other things on the growth conditions; wet conditions can for instance lead to pre-harvest sprouting of the grain, with increased levels of alpha-amylase and protease activity and poor baking performance as a result. Wet conditions may lead to pre-harvest sprouting of the grain, with too high levels of alpha-amylase and protease activity and poor baking performance as a result. Wheat flour normally contains relatively high and consistent amounts of beta-amylase, whereas the alpha amylase levels are generally lower. A certain amount of alpha-amylase activity in the flour is needed for a good baking performance.
One of the main challenges in the baking industry is to ensure a consistent quality of baked goods, regardless of the quality of the flour used. To achieve a consistent baking performance flour quality is being standardized. Flour quality is checked at two distinct points in the process from grain harvest to final baked product: at the mill and by the bread improver/bakery. Whereas at the bread improvers/bakeries a range of enzymes are added to produce high specialty flours aimed at specific applications, the aim of the mill is generally to produce a standard flour that can be traded in the market.
At the mill, flour is evaluated on a number of parameters such as moisture, protein content and ash content. In addition, a standard procedure, the falling number test, is performed to measure the alpha-amylase activity. If too little amylase activity is found, the flour can be “corrected” to meet a standard by adding exogenous alpha-amylase, for example in the form of malt flour or by using a fungal amylase. Malt flour has one clear advantage over fungal amylase: it can be used in the falling number test because it influences the falling number. Fungal amylase is less thermostable than malt flour and quickly becomes inactivated in the falling number test procedure. A disadvantage of currently known fungal amylases is that they are less thermostable than alpha-amylase present in malt flour.
During the falling number test procedure, which is performed at temperatures close to 100 degrees Celsius, currently known fungal amylases get more quickly inactivated than alpha-amylase present in malt flour.
Therefore the presence of fungal amylase is not visible in the falling number test. Since the falling number test is a standard procedure this is seen as a disadvantage in the milling industry.
Alpha amylases are also used in other industrial sectors, such as the beverage industry, the brewing industry, the textile industry, the paper industry, the detergent industry, the pharmaceutical industry and the plastics industry, where amylases are used in the production of maltodextrin, modified starches, or glucose and fructose syrups, in the clarification of beer, for desizing textile, for starch modification for coating papers, for the removal of stains and in the production of starch based bioplastics.